1. Field of the Invention
The present invention relates generally to medical devices for diagnostic and therapeutic applications, and more particularly, relates to construction and use of catheters for diagnostic and therapeutic applications.
2. Description of the Prior Art
Catheters have been in general use for some time in the medical field for a wide range of applications. These include uses within the cardiovascular system, urinary tract, etc. A number of these applications are diagnostic in nature, such as the injection of dyes in angiography. Other applications are therapeutic in nature such as angioplasty. Still others simply involve the transfer of a liquid such as blood, nutrients, or pharmaceuticals.
In many catheter applications, a multilumen catheter is used wherein a first lumen is open for a portion of the procedure. A lumen is open when it has one or more orifices located near the distal end. In addition to an orifice at the tip, many infusion catheters locate the orifices along the catheter body. These orifices may provide for the transfer of a liquid, such as in a blood transfusion or urinary bladder catheterization, or may be a mechanical convenience as in a procedure wherein the catheter is slid over a previously positioned guide wire.
Most commonly, a separate lumen is employed for each function. However, it is often desirable that an open lumen also be closed for a portion of the medical procedure to permit a single lumen to perform more than one function. It is also often desirable to close an open lumen to prevent the ingress or egress of certain gases or liquids.
A prior technique for closing a lumen during a portion of a medical procedure involves using a guide wire having a seal at its distal tip to be moved in a proximal direction relative to the catheter until sealing engagement at the distal tip of the catheter is accomplished. This technique, however, requires the use of a guide wire and can usually only close a lumen which is open at the distal tip of the catheter. The seal is often less than satisfactory as well.